1. Field of the Invention
The present invention relates to an electron energy analyzing apparatus, and more particularly to an apparatus for analyzing the energy of electrons which have passed through a sample.
2. Description of the Prior Art
When an electron beam is incident upon a sample, some of the electrons having passed through the sample do not lose any energy, but the remaining ones lose some energy due to the interaction between the electrons and the sample. Since the energy loss of such electrons depends upon substances making up the sample, it is possible to analyze the constituent substances of the sample on the basis of an energy spectrum of the electrons which have passed through the sample.
When electrons which have passed through a sample are introduced into an electron analyzer, the electrons are dispersed in accordance with their energy. Accordingly, when the energy analyzer is so set as to detect only an energy loss peak caused by a specified substance contained in the sample in order to apply an energy loss peak signal thus obtained to a cathode ray tube as a brilliance modulation signal, and when the sample is two dimensionally scanned by an electron beam and the screen of the cathode ray tube is two-dimensionally scanned by the electron beam of the tube in synchronism with the scanning motion for the sample, an image showing a distribution of the specified substance can be displayed on the screen of the cathode ray tube. This distribution image is usually called the element mapping image.
In the above-mentioned case, however, there arises a problem that the energy loss peak signal which is actually detected, includes a background component which increases with the thickness of the sample.